The Syrian authorities say three people were killed in an explosion on a bus in the capital Damascus.

Other reports say six people died.

A Syrian minister has told the press that the explosion was caused when a rear tyre burst while the bus was refueling. He said it was not a terrorist attack.

The bus was carrying mainly Shiite pilgrims from Iran. They were on a pilgrimage to a Shiite shrine on the outskirts of Damascus.

Last year in September, at least 17 people died in the same neighbourhood when a car bomb exploded. No-one has ever claimed responsibility for the attack, but Sunni extremists are thought to have been behind it.